Soil Water Samples Research Articles

Snowmelt-mediated isotopic homogenization of shallow till soil

Abstract. The hydrological cycle of sub-arctic areas is dominated by the snowmelt event. An understanding of the mechanisms that control water fluxes during high-volume infiltration events in sub-arctic till soils is needed to assess how future changes in the timing and magnitude of snowmelt can affect soil water storage dynamics. We conducted a tracer experiment in which deuterated water was used to irrigate a plot on a forested hilltop in Lapland, tracked water fluxes of different mobility and monitored how the later snowmelt modifies the labelled soil water storage. We used lysimeters and destructive soil coring for soil water sampling and monitored and sampled the groundwater. Large spatiotemporal variability between the waters of different mobility was observed in the subsurface, while surface water flow during the tracer experiment was largely controlled by a fill-and-spill mechanism. Extensive soil saturation induced the flow of labelled water into the roots of nearby trees. We found that labelled water remained in deeper soil layers over the winter, but the snowmelt event gradually displaced all deuterated water and fully homogenized all water fluxes at the soil–vegetation interface. The conditions required for the full displacement of the old soil water occur only during a snowmelt with a persistently high groundwater table. We propose a conceptual model where infiltration into the soil and eventual soil water replenishment occur in three stages. First, unsaturated macropore flow is initiated via the surface microtopography and is directed towards the groundwater storage. The second stage is characterized by groundwater rise through the macropore network, subsequent pore water saturation and increased horizontal connectivity of macropores. Shallow subsurface lateral fluxes develop in more permeable shallow soil layers. In the third stage, which materializes during a long period with a high groundwater table and high hydrological connectivity within the soil, the soil water is replenished via enhanced matrix flow and pore water exchange with the macropore network.

Persistence of Helicobacter Pylori Coccoid Forms in Different Environments

Objective: The present study aims to determine the possibility of H. pylori coccoid forms to survive in our surrounding environments, thus exhibiting public health hazard. Method: Helicobacter pylori strain Makkah 7 accession number HQ622108, was inoculated in samples of soil, well, tap, swimming pool, and sewage water; in which, an average initial inoculum of 107 CFU/ml was inoculated. The experiment was conducted, outdoor where ambient temperature varied between 39-55°C in Jeddah city, Saudi Arabia. The survival rate of H. pylori strain was quantitatively and qualitatively studied for five months. Results: Viable counts were undetectable after 24 hours, while total count varied between 107 to 106, and declined to 103 bacterial cell/ml five months later. Interestingly, microscopic examination revealed few non-motile rods and motile coccoid forms. All samples were removed and placed at 4°C for one month. Following, total count, morphology, and motility were examined, showing motile coccoid forms. Electron microscopic and, molecular studies were carried out, confirming that the species is H. pylori, which was detected by using 16S rRNA primer for H. pylori with a product size of 163 bp. The ability of H. pylori strain to persist and survive, by being motile in the coccoid form, for five months under such hostile environment, strongly indicates that the coccoid form plays a vital role in the transmission, recrudescence, and therapeutic failure. It is indeed a hazardous and a crucial infectious phase of this bacterium. Conclusion: Detecting coccoid forms in water and soil, accompanied by their eradication, must be seriously considered and applied. Consequently, hindering and preventing different diseases caused by H. pylori.

Radiometric hazard assessment of soil and water samples adjacent to Bangladesh's first nuclear power plant before commissioning: Insights into human health and environmental radiological dynamics

The current study provides a comprehensive examination of both natural and anthropogenic activity concentrations found in soil and surface water samples near the Rooppur nuclear power plant (RNPP), the first of its kind under construction in Bangladesh. The investigation covers a range of activity concentrations including 226Ra, 232Th, and 40K in fifty soil and fifty water samples, revealing values ranging from 18 to 38, 18–51, and 310–560 Bqkg−1 for soil, and 2.1–6.1, 2.1–5.5, and 67–115 Bqkg−1 for water, respectively. Although outdoor absorbed dose rate, outdoor effective dose, and gamma representative level index values in some soil samples exceed global averages, other radiological hazard parameters such as radium equivalent activity, annual effective dose, external and internal hazard indices, and lifetime carcinogenic risk for both soil and water samples consistently remain below safety thresholds established by international organizations. These findings indicate that the soil and water samples collected from the vicinity of the RNPP do not pose significant radiological hazards to the nearby populations. This study's comprehensive dataset is anticipated to play a crucial role in facilitating the identification and evaluation of any changes in environmental radioactivity, thereby assisting in the effective management and regulation of nuclear power plant activities in the years to come.

Measuring shrinkage of expansive soils using a novel automated high‐frequency setup

AbstractSoil shrinkage characteristic curves are used to describe the shrinkage behavior and hydraulic properties of unsaturated soils. To construct soil shrinkage characteristic curves, a high‐data‐density measurement method is needed that relates water content to soil volume changes. We present a fully automated soil shrinkage measurement setup, based on the simplified evaporation method, to characterize the shrinkage behavior of undisturbed natural expansive clay soils. The high data density creates the opportunity to produce soil shrinkage characteristic curves without the need for a mathematical model. The technique allows for resaturation of the samples after drying, enabling differentiation between reversible and irreversible shrinkage. The setup consists of the commercialized HYPROP2 apparatus combined with optical distance sensors to measure the horizontal and vertical dimensions of the samples, yielding data on the sample volume, weight, and soil water suction. The measurement frequency is once per 10 min, and the measurement period is up to 4 weeks, providing a detailed time series of the drying and shrinkage characteristics. The setup can capture the different shrinkage phases and offers the opportunity to relate the soil shrinkage characteristic curve to soil water suction. The measurement data acquisition rate and accuracy enable detailed interpretation of soil water retention curves for nonrigid soils and are shown to be essential for understanding and quantifying the shrinkage potential of several types of deposits.

Potentially toxic metals in Northeast Ethiopian agricultural soils: implications for Solanum lycopersicum (Tomato) production and human health.

Exposure to heavy metal-contaminated vegetables, irrigation water and agricultural soil is one of the most challenging environmental issues worldwide. This study aimed to evaluate the health effects of potentially toxic metals (PTMs) including Cr, Cd, Fe, Pb, Cu, Zn, and Co from agricultural soil, irrigation water, and tomato plants collected from the Abuarie irrigation site, Northeast Ethiopia. The samples were digested using acid digestion method, and its concentration was quantified using Inductively Coupled Plasma-Optical Emission Spectroscopy. The concentrations of PTMs in the soil, tomato, and irrigation water samples ranged from 49,020 ± 275 (Fe) to 11.85 ± 0.44 (Cd), 170 ± 1.98 (Fe) to 0.29 ± 0.006 (Cd) mgkg-1, and 0.24 ± 0.003 (Fe) to 0.025 ± 0.005(Ni)mgL-1 , respectively. The results revealed Zn, Ni, Cd and Cr in soil, all metals in tomato, and Cu, Ni, Cd and Pb in irrigation water sample were above the World Health Organization threshold values. Moreover, the separate and cumulative exposure to farm soil, irrigation water, and consumption of tomato were investigated using the hazard quotient (HQ) and hazard index (HI) values, respectively. The results revealed that individual exposure to each sample type did not have a significant impact on health (HQ < 1). However, simultaneous exposure to all of the sample types (soil, tomato and irrigation water) at the same time had a high likelihood of affecting health (HI > 1). The total carcinogenic concentrations of Cr, Cd, Ni, and Pb were greater than 1 × 10-4, revealing that farmers have a high probability of developing cancer during their lifetime. Minimizing simultaneous exposure to soil, tomato, and irrigated water for local people is highly recommended to prevent the risk of PTMs.

Development of dispersive solid phase extraction method for the preconcentration of parathion ethyl as a simulant of nerve agent sarin from soil, plant and water samples prior to GC-MS determination.

In the presented study, an efficient and fast analytical method was developed for the determination of parathion ethyl as sarin simulant by gas chromatography-mass spectrometry (GC-MS). Dispersive solid phase extraction (DSPE) was performed to concentrate parathion ethyl from soil, plant and water samples. Reduced graphene oxide-iron (II, III) oxide (rGO-Fe3O4) nanocomposite was used as an adsorbent to collect the target analyte from the aqueous sample solutions. After the optimization of extraction/preconcentration parameters, optimum conditions for adsorbent amount, eluent type, mixing type/period, eluent volume and initial sample volume were determined as 15mg, acetonitrile, vortex/30s, 100 µL and 10mL, respectively. Under the optimum conditions, analytical performance of the developed DSPE-GC-MS method was evaluated in terms of limit of detection (LOD), limit of quantitation (LOQ) and dynamic range. Dynamic range, LOD and LOQ values were figured out to be 0.94-235.15µg/kg, 0.41µg/kg and 1.36µg/kg (mass based), respectively. Satisfactory percent recovery results (90.3-125% for soil, 93.5-108.7% for plant, 88.5-112.9% for tap water) were achieved for soil, plant and tap water samples which proved the accuracy and applicability of the developed method. It is predicted that the DSPE-GC-MS method can be accurately used for the detection of sarin in soil, plant and water samples taken from war territories.

A novel coumarin based fluorescent sensor for high-sensitive detection of Cu2+ and water as well as applications in food and environmental analysis

A novel fluorescent sensor (SZ) based on coumarin was designed and synthesized for the detection of Cu2+ in DMSO/H2O solution (9/1, v/v, pH = 7.4, HEPES = 10 mM) and water in organic solvents. The sensor exhibited a low detection limit of 9.6 × 10−8 mol/L and a short response time (30 s) for Cu2+ in DMSO/H2O solution. SZ showed a red-shift in emission wavelength in more polar solvents and demonstrated high sensitivity in detecting water in various solvents including tetrahydrofuran, acetone, ethanol, methanol and acetonitrile with the lowest detection limit in ethanol as low as 0.0035 % (v/v). The mechanism for water detection by SZ was identified to be polarity dependent. Moreover, SZ was effectively employed for detecting alcohol content in Chinese Baijiu, as well as water content in sugar and salt samples. Notably, SZ has the capability to determine Cu2+ in soil and environmental water samples, showing a wide range of potential applications.

ANALYZING THE EXTENT OF LEACHATE FROM A MAJOR DUMPSITE WITHIN THE CRETACEOUS SEDIMENTS OF IKOM-MAMFE EMBAYMENT, SOUTHEAST NIGERIA

Groundwater resources in the region serve as a vital source of potable water for local communities and are essential for supporting various socio-economic activities. Unfortunately, the infiltration of leachate from dumpsite contributes to the dispersion of contaminants within the cretaceous sediments, posing a potential threat to groundwater quality. This study presents an exhaustive examination of leachate extent emanating from a prominent dumpsite situated within the Cretaceous sediments of the Ikom-Mamfe Embayment, Southeast Nigeria. Employing meticulous soil sampling methodologies and water collection from strategically positioned boreholes near the Ikom dumpsite, advanced techniques such as Electrical Resistivity Tomography (ERT) and Vertical Electric Sounding (VES) were utilized to scrutinize the infiltration of leachate within the site. Laboratory analyses were conducted to evaluate the concentrations of heavy metals, including Lead, Mercury, Arsenic, Nickel, Chromium, and Cadmium, in both soil and borehole water samples. The findings unveiled alarming levels of Lead and Cadmium concentrations in the soil, exceeding established regulatory thresholds, with recorded values ranging from 552.34 to 556.93 mg/kg and 11.88 to 7.46 mg/kg, respectively. Similarly, borehole water analyses in the vicinity of the Ikom dumpsite revealed elevated concentrations of Arsenic, Lead, Cadmium, and Nickel, surpassing WHO limits in specific boreholes (BH2 and BH3), indicative of potential soil porosity issues and unfavorable geological conditions prevalent in the study area. Notably, the use of ERT delineated an inverse resistivity of 5.99 Ωm at a depth of 9.26 m, pinpointing the leachate-infiltrated cretaceous sediments zone, extending laterally from 10m to 40m along the profile. The observed infiltration of leachate at 9.26 m depth underscores its penetration into the sandstone, shale, and dark gray shale strata within the dumpsite. Furthermore, the quantified thickness layer ranging from 1.41 to 4.37 affirmed leachate infiltration within the sandstone, shale, and dark gray shale strata, with implications for its movement and containment dynamics. This study underscores the critical role of layer thickness in influencing the migration and containment of leachate, with thicker layers potentially acting as barriers to its movement, while thinner layers may facilitate more rapid migration. Additionally, the assessment of aquifer protective capacity, denoted by ratings below (&lt;0.1), underscores the poor protective capacity of the aquifer system in the study area. In light of these findings, strategic management, remediation, and vigilant monitoring measures are advocated to mitigate contamination risks and safeguard water quality.

Radiation protection for Gabes phosphate area residents: Assessing natural radioactivity in soil and potable water samples

Phosphate mining activities are recognized to be one of various industrial processes generating enhanced Naturally Occurring Radioactive Materials (NORM) by introducing natural radionuclides into the surrounding soils and water bodies, posing a risk to human health.This study was carried out to assess the level of natural radionuclides in soils and potable waters collected from the phosphate area of Gabes city, located in southeastern Tunisia, and to evaluate radiation protection measures by estimating radiological health hazard parameters. Gamma spectrometry system employing an HPGe detector was used in this study to assess 40K, 232Th and 226Ra activity concentration in soils. The average values were found to be 163.7, 14.5, and 7.7 Bq kg−1, respectively, which were lower than worldwide average values. The radiological hazard parameters assessed in this study were radium equivalent activity (Ra-eq), external hazard index (Hex), external gamma absorbed rate (GDR), external annual effective dose (Deff) and excess lifetime cancer risk (ELCR). The calculated average values of the above-mentioned parameters were of 41 Bq kg−1, 0.1, 20.2 nGy h−1, 24.8 μSv y−1 and 8.7 × 10−5 all of which were found to be below their permissible standards.For potable water samples, the activity concentrations of radium were analyzed using an HPGe detector and those of uranium were determined by alpha spectrometry. The average activity concentrations of uranium and radium isotopes in underground water samples were found to be higher than those obtained in tap water samples. For both types of water, the average values for all radionuclides were found to be below their respective reference limits.The annual ingestion effective doses were also estimated in this study. The estimated average values for infant and children for underground water samples were higher than the permissible limit of 100 μSv y−1 set by WHO. The 226Ra was the main contributor to the effective doses for different age categories, followed by 228Ra.

Tracing sources of dissolved organic matter along the terrestrial-aquatic continuum in the Ore Mountains, Germany

There is growing concern about the rising levels of dissolved organic matter (DOM) in surface waters across the Northern hemisphere. However, only limited research has been conducted to unveil its precise origin. Compositional changes along terrestrial-aquatic pathways can help determine the terrestrial sources of DOM in streams. Stream water, soil water and soil horizons were sampled at four sites representing typical settings within a forested catchment in the Ore Mountains (Erzgebirge, Germany) from winter 2020 to spring 2022. The samples were analyzed using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The resulting data were successfully subjected to semi-automatic processing of the molecular composition of DOM, reaching a percentage of identified peaks up to 98 %. Principal component analysis (PCA) and cluster analyses were carried out to identify distinct differences between DOM from the potential sources and in the streams. According to the PCA, organic soil horizons, soil water, and stream water samples could be clearly distinguished. Cluster analysis revealed that soil water DOM at all depths of Peats and deeper horizons of the Peaty Gleysols contributed the most to DOM in the stream section dominated by organic soils. In areas dominated by mineral soils, stream DOM resembled the DOM from the deeper mineral horizons of Cambisols and Podzols. Overall, our results suggested that most of the DOM exported from the catchment was derived from deeper mineral soil horizons, with little contribution of DOM derived from organic soils. Therefore, DOM fingerprint analysis of in-situ soil water proved to be a promising approach for tracing back the main sources of stream water DOM.

Level of Heavy Metals and Potential Ecological Risks in Irrigated Horticultural Farms in the Vicinity of Lake Ziway, Central Ethiopian Rift Valley Region.

Research on heavy metal pollution in horticultural farms located around lakes in the Central Ethiopian Rift Valley Region has focused on measuring the levels of heavy metals and their health implications. However, the ecological risks of horticultural farms contaminated with heavy metals in this region have not been studied. The current study addresses this gap by providing information on the degree of heavy metal contamination and the ecological risk associated with horticultural farms around Lake Ziway, using various pollution indices. An inductively coupled plasma optical emission spectrometer (ICP-OES) was used to measure the concentrations of nine heavy metals (As, Cd, Co, Cu, Cr, Ni, Pb, Hg, and Zn) in a total of 30 composite soil and irrigation water samples, each consisting of a mix of six subsamples. The results indicated that the mean concentrations of Hg, Cd, Pb, and Zn in soils collected from all the sampling sites exceeded the FAO/WHO maximum permissible limit (MPL). The values of both the contamination factor (CF) and contamination degree (Cd) of the heavy metals ranged from 0.04 to 2.66 and 2.81 to 6.14, respectively, indicating a low to medium level of contamination for both indices. The pollution load index (PLI) values of 0.451, 0.449, and 0.157 for sites 2, 1, and 3, respectively, indicate "unpolluted" to "moderately polluted" levels of heavy metal pollution. However, the ecological risk indices (ERIs) at sites 2 and 1 (158.92 and 141, respectively) showed a potentially high ecological risk due to soil pollution. Therefore, close monitoring and early intervention mechanisms must be in place to control pollution in the study area.

Pollution characteristics and risk assessment of organophosphate esters (OPEs) in typical industrial parks in Southwest China.

As alternative substances of PBDEs, organophosphate esters (OPEs), an emerging organic pollutant, were increasingly produced and used in many kinds of industries and consumer products. However, OPEs also have various adverse toxic effects. Information on the pollution levels and exposure to OPEs in related industries is still limited. This study presented data on OPE contamination in the soil, leaf, and river water samples from seven typical industrial parks in Southwest China. Total concentration of seven OPEs (Σ7OPE) including tri-n-butyl phosphate (TnBP), tris-(2-ethylhexyl) phosphate (TEHP), tris-(2-butoxyethyl) phosphate (TBEP), tris-(2-carboxyethyl) phosphine (TCEP), triphenyl phosphate (TPhP), tris-(1,3-dichloro-2-propyl) ester (TDCPP), and tris-(chlorisopropyl) phosphate (TCPP) in the soil samples (36.2 ~ 219.7 ng/g) and the surrounding river water samples (118.9 ~ 287.7 ng/L) were mostly lower than those in other studies, while the Σ7OPE level in the leaves (2053.3 ~ 8152.7 ng/g) was relatively high. There were significant differences in the concentration and distribution of OPEs in the surrounding environment of different industrial parks. TDCPP, TnBP, and TCPP could be used as the characteristic compound in soil samples from auto industrial park, river samples from shoe making industrial park, and leaf samples from logistics park, respectively. The parameter m (the content ratio of chlorinated OPEs to alkyl OPEs) was suggested to distinguish the types of industrial park preliminary. When m ≥ 1, it mainly refers to heavy industries sources such as automobiles, electronics, and machinery, etc. When m<1, it mainly for the light industrial sources such as textile industry, transportation services, and resources processing, etc. For logistics park, furniture park and Wuhou comprehensive industrial park, the volatilization of materials was the main sources of OPEs in the surrounding environment, while more effort was required to strengthen the pollution control and management of the waste water and soil in the pharmacy industrial park, shoe making industrial park and auto industrial park. Risk assessment showed that there was a negligible non-cancer and carcinogenic risk in the soil, while high attention should be paid to the non-cancer risk for children.

Evapotranspiration variation of soil‐plant‐atmosphere continuum in subalpine scrubland of Qilian Mountains in China

AbstractThe water cycle in the soil‐plant‐atmosphere continuum is an important element of hydrological and ecological studies, and differences in the composition characteristics of hydrogen and oxygen stable isotopes in different water bodies can indicate water cycling processes. In this study, hydrogen and oxygen isotopes of precipitation, soil water and plant water samples had been collected in the subalpine scrubland of the Qilian Mountains from May to October 2019. The Craig‐Gordon model, the isotopic steady‐state (ISS) assumption, the Keeling Plot model and the two‐source mixing model were used to analyse the stable isotope compositions of different water bodies, the stable isotope characteristics of water vapour of soil evaporation and plant transpiration and the variation of evapotranspiration in the SPAC of the subalpine scrubland. The results showed that plant transpiration (FT) contributed 87.28% and 86.95% to evapotranspiration and soil evaporation (FE) contributed 12.72% and 13.05% to evapotranspiration in the growing season on semi‐sunny and semi‐shaded aspects, respectively, indicating that evapotranspiration in the subalpine scrubland mainly came from the transpiration of scrubland plants. In the early of the growing season (May–June), due to the rapid expansion of plant leaves, the contribution of transpiration to evapotranspiration was at a high level, which intensified transpiration and led to a gradual increase of the transpiration contribution. In the middle of the growing season (July–August), owing to better conditions of rain and heat that made plants grow vigorously, plant transpiration made the highest contribution to evapotranspiration more than 90%, which caused to an overwhelming contribution of plant transpiration to evapotranspiration. In the later of growing season (September to October), the contribution of plant transpiration to evapotranspiration decreased significantly while that of soil evaporation increased, which was because plant photosynthesis and respiration gradually declined for losing their leaves of scrub plants and the relative atmospheric humidity was lower.

Synergistic optical sensing: Selective colorimetric analysis of copper in environmental and biological samples

A groundbreaking optical sensing membrane has been engineered for the accurate assessment of copper ions. The pliable poly(vinyl chloride) membrane is formulated through the integration of sodium tetraphenylborate (Na-TPB), 4-(2-hydroxy-4-nitro azobenzene)-2-methyl-quinoline (HNAMQ), and tri-n-octyl phosphine oxide (TOPO), in conjunction with o-nitrophenyl octyl ether (o-NPOE). The sensor membrane undergoes a thorough investigation of its composition to optimize performance, revealing that HNAMQ serves a dual role as both an ionophore and a chromoionophore. Simultaneously, TOPO contributes to enhancing the complexation of HNAMQ with copper ions. Demonstrating a linear range for Cu2+ ions spanning from 5.0 × 10−9 to 7.5 × 10−6 M, the proposed sensor membrane showcases detection and quantification limits of 1.5 × 10−9 and 5.0 × 10−9 M, respectively. Rigorous assessments of potential interferences from other cations and anions revealed no observable disruptions in the detection of Cu2+. With no discernible HNAMQ leaching, the membrane demonstrates rapid response times and excellent durability. The sensor exhibits remarkable selectivity for Cu2+ ions and can be regenerated through exposure to 0.05 M EDTA. Successful application of the sensor in determining the presence of Cu2+ in biological (blood, liver and meat), soil, food (coffee, black tea, sour cherry juice, black currant, and milk powder) and environmental water samples underscores its efficacy.

Prevalence and Genomic Investigation of Salmonella Isolates Associated with Watermelons and Their Environmental Reservoirs in Bejaia, Algeria.

This study was conducted in Bejaia, Algeria, to determine the presence of Salmonella in fresh watermelon (n = 105), soil (n = 23), and irrigation water samples (n = 17) collected from two different farms. After isolation, antimicrobial susceptibility testing, serotype determination, multilocus sequence typing, antimicrobial resistance genes detection, and whole genome sequencing were performed. Twenty watermelon samples (19%) were contaminated with Salmonella, but none were found in the soil or irrigation water. Among the 20 Salmonella isolates, 2 serovars were identified (Salmonella Liverpool and Salmonella Anatum), belonging to sequence types ST1959 and ST64, respectively. Ten Salmonella isolates showed significant resistance to nalidixic acid, ofloxacin, and ciprofloxacin but were susceptible to all other antibiotics. The coexistence of point mutations (parC:p.T57S) in Quinolone Resistance-Determining Regions and the qnrB19 gene may contribute to quinolone resistance. The study identified 164 virulence genes in the Salmonella isolates. Our study found Salmonella in fresh watermelon during the preharvest season in Bejaia, Algeria. Our study indicates a relatively high prevalence of Salmonella on watermelon samples before harvest. Although we cannot directly compare our results with previous studies, it is crucial to recognize that the absence of comprehensive comparative data underscores the need for further research and surveillance.

Surveillance and source tracking of foodborne pathogens in the vegetable production systems of India

Fresh vegetables are prone to foodborne pathogen infection due to improper cultivation methods and poor post-harvest handling practices. This paper describes the prevalence of foodborne pathogens in three vegetables (tomato, brinjal, and lablab) cultivated by small-scale producers (SSP) of India. We assessed the possible entry of pathogens into the vegetable production chain. Samples from soil, manure, irrigation water, harvesting bins, and workers’ hands were assessed as sources of possible pathogen entry. In addition, further sampling was done to determine prevalence of these pathogens in the produce from the agricultural fields and markets. Total plate counts, yeast and mold count, total coliforms like general microbial indices, and possible foodborne pathogens like Salmonella, Escherichia coli O157, Staphylococcus aureus, Pseudomonas aeruginosa, and norovirus were assessed in all the samples by standard microbiological, biochemical, and molecular methods. The results revealed that among the three vegetables we studied, brinjal had the highest load of general microbial indicators. Moreover, the total coliforms count of market vegetables was higher than that of on-farm vegetables, indicating poor hygiene in post-harvest operations. The pathogen Pseudomonas aeruginosa was found in the market tomatoes (0.35 log10 cfu/g), and E. coli was detected in the market samples of brinjal (2.98–3.89 log10 cfu/g) and lablab (0.59–2.21 log10 cfu/g), thereby revealing fecal cross-contamination during pre or post-harvest operations. None of the vegetable samples were contaminated with E. coli O157:H7, Staphylococcus aureus, Salmonella sp., and norovirus. However, the microbiological source tracking of primary production farms showed that E. coli O157:H7 was present in manure (9/27), soil (6/27), harvest bins (6/27), and irrigation water samples (3/27) of SSP farms. In addition, soil (33%), manure (11%), and harvest bins (11%) had Pseudomonas aeruginosa. In conclusion, our study suggests that adequate knowledge of good agricultural practices for small-scale producers to cultivate microbiologically safe vegetable production and proper handling strategies for vegetable vendors is crucial to mitigate foodborne pathogen outbreaks through fresh vegetables.

Label-free, liquid crystal-based aptasensor for detecting carbendazim at picomolar levels

We describe a simple and sensitive liquid–crystal (LC)-based method for quantifying carbendazim (CBZ) by exploiting aptamer-specific recognition at the aqueous-LC interface. The method relies on the interfacial interaction between an aptamer and cetyltrimethylammonium bromide (CTAB); this interaction varies depending on the amount of CBZ. In the absence of CBZ, the aptamer disrupts the CTAB monolayer through electrostatic attraction, leading to a transition from homeotropic to tilted ordering of the LCs. As CBZ concentrations rise, the formation of aptamer-CBZ complexes increases, preserving the vertical alignment of the LCs by reducing collapse of the CTAB layer caused by electrostatic interactions. Using these methods, we achieved a CBZ detection limit of 3.12 pM (0.000597 μg/L) over a linear range of 0.05–5 nM. Moreover, we quantified CBZ levels in peach, soil, and tap water samples. Our LC-based detection method has significant research potential, offering sensitive, and straightforward detection of CBZ.

Soil water sources and their implications for vegetation restoration in the Three-Rivers Headwater Region during different ablation periods

Abstract. Amid global warming, the timely supplementation of soil water is crucial for the effective restoration and protection of the ecosystem. It is therefore of great importance to understand the temporal and spatial variations of soil water sources. The research collected 2451 samples of soil water, precipitation, river water, ground ice, supra-permafrost water, and glacier snow meltwater in June, August, and September 2020. The goal was to quantify the contribution of various water sources to soil water in the Three-Rivers Headwater Region (China) during different ablation periods. The findings revealed that precipitation, ground ice, and snow meltwater constituted approximately 72 %, 20 %, and 8 % of soil water during the early ablation period. The snow is fully liquefied during the latter part of the ablation period, with precipitation contributing approximately 90 % and 94 % of soil water, respectively. These recharges also varied markedly with altitude and vegetation type. The study identified several influencing factors on soil water sources, including temperature, precipitation, vegetation, evapotranspiration, and the freeze–thaw cycle. However, soil water loss will further exacerbate vegetation degradation and pose a significant threat to the ecological security of the “Chinese Water Tower”. It emphasizes the importance of monitoring soil water, addressing vegetation degradation related to soil water loss, and determining reasonable soil and water conservation and vegetation restoration models.

From ground to gut: Evaluating the human health risk of potentially toxic elements in soil, groundwater, and their uptake by Cocos nucifera in arsenic-contaminated environments

This study aimed to gauge the toxicity of potentially toxic elements (PTEs) in coconut crops cultivated in arsenic-contaminated areas while offering a global perspective encompassing more than 100 impacted countries. The current investigation provides crucial insights into the assessment of PTEs pollution using the Bioaccumulation factor, Geo-accumulation index, Potential ecological risk index, Hazardous index, and Lifetime cancer risk (LCR) and highlights the potential human health risks posed by contaminated food, water, and soil. From 22 severely polluted sites in West Bengal, India, soil, groundwater (GW), and coconut water (CW) samples were collected, acidified, and digested using microwave digestion, for PTEs quantification using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Results revealed that despite high concentrations of arsenic in soils (4.6 ± 3.4 mg kg−1), and GW (22.2 ± 150.9 μg L−1), CW (0.7 ± 3.1 μg L−1) levels were within permissible limits. Groups of PTEs with comparable sources and distributions were discovered through Principal Component Analysis (PCA). A speciation diagram was used to predict the prevalence of arsenic species in all three matrices. The Hazardous Index (HI < 1) indicated no probability of non-carcinogenic diseases for children and adults in all the compartments. However, exposure to GW and soil contaminated with Cr, As, and Cd by children (9.02 × 10−13 to 2.77 × 10−4) and adults (6.51 × 10−14 to 1.18 × 10−4) would increase their susceptibility to cancer (LCR >10−6). The study concluded that moderate lifetime consumption of CW is safe and has no significant impact on healthy individuals. Additionally, CW is a rich source of essential micronutrients such as Zn, Fe, Mn, and B. Overall, the findings of this study could help in developing appropriate strategies for reducing PTEs contamination and protecting human health.

Sensitive and selective electrochemical characterization and analytical determination of linezolid in environmental samples using TiO2 nanoparticles and MWCNT-COOH modified glassy carbon electrode

In this study, a sensitive, selective, and applicable electrochemical method based on the oxidation of linezolid active material was developed using a bare glassy carbon electrode (GCE) and modified glassy carbon electrodes treated with titanium dioxide nanoparticles/carboxyl-function multi-walled carbon nanotubes (TiO2/MWCNT-COOH/GCE). The surface characterization of the developed TiO2/MWCNT-COOH/GCE was examined using scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The electrochemical properties of the linezolid substance were investigated using cyclic voltammetry. Furthermore, drug determination was carried out by differential pulse voltammetry (DPV) and absorptive stripping differential pulse voltammetry (AdSDPV). The linearity range under optimized conditions was determined as 1–20 µM and 0.2–2.0 µM on the bare GCE and TiO2/MWCNT-COOH modified electrode, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.0365 µM and 0.1215 µM for bare GCE, and 0.00056 µM and 0.00188 µM for TiO2/MWCNT-COOH/GCE, respectively. Interference studies were also performed by the developed sensor with various inorganic and organic substances that could affect LNZ detection. Then, the proposed sensor was applied for the determination of LNZ in real samples such as soil, tap water, and natural spring water samples, and the accuracy of the proposed method was proven in recovery studies, with values of 99.90 %, 100.94 %, and 101.17 %, respectively. In conclusion, a new sensor with high recovery, low relative error, and high selectivity was successfully produced and applied to detect LNZ in actual samples.